摘要： 基于模式匹配的入侵检测是目前最重要的一种入侵检测方法，而字符串匹配效率是该方法的核心，直接影响检测效率。该文在充分分析BM 算法、AC 算法及AC_BM 算法的基础上提出了一种新的更好搜索步长的多模式匹配算法NMSA，并具体分析了该算法的效率。通过实验数据对比，再次证明NMSA 算法具有更好的搜索步长、更好的效率。

关键词: 入侵检测；多模式匹配；NMSA 算法

Abstract: At present, the patterns matching-based algorithms to network intrusion detection are the very important methods in intrusion detection, and the core of this is the efficiency of string matching which influences the efficiency of detection directly. This paper analyzes some string matching algorithms, such as BM algorithm, AC algorithm and AC_BM algorithm, and then presents a new multi pattern matching algorithm with the longer steps. It shows analytically and experimentally that the new algorithm is faster in the searching larger sets of patterns

Key words: Intrusion detection; Multi-pattern matching; NMSA algorithm